1. Field of the Invention
The present invention generally relates to a leaf construction for mounting display articles such as photographs, name cards, newspaper clippings in albums, scrapbooks and the like.
2. Prior Art
It is known to use corner retainers having a glued back and a pouched triangular insert for holding the corners of photographs and similar flat display articles firmly onto the loose leaves or pages of albums and scrapbooks. Display articles mounted in this manner tend, however, easily to move from their original positions and, in some cases, even to drop off the leaves. Furthermore, it is troublesome to dispose such retainers at the proper locations and also to apply them to the loose leaves.
Photographs or the like may of course be glued directly to the leaves but this is likewise inconvenient and often, with time, the glued articles curl and come loose. Furthermore, the chemical composition of which the glue is made sometimes stain the display articles.
An appreciable improvement in mounting leaves for displaying articles has been made by the use of a cardboard base having a pressure-sensitive adhesive composition printed on at least one of its faces, as disclosed in my prior U.S. Pat. Nos. 3,670,434 of June 13, 1972 and 3,736,685 of June 5, 1973. The cardboard base in the loose leaves of these U.S. Patents, over which the adhesive composition is applied, is covered with a transparent sheet of plastics material; the photographs and other similar articles to be displayed being mounted between the base and this transparent sheet cover so that they can clearly be viewed. Such cardboard base has a tendency to absorb or expel moisture depending upon the humidity of the ambient atmosphere and tends also to expand or shrink due to such absorption of expulsion of moisture. In contrast, the cover sheet of transparent plastics material is little affected by a change in the humidity of the normal ambient atmosphere. As this cover sheet does not stick very much to the base through the pressure-sensitive adhesive composition, shrinkage or expansion of the base causes the cover sheet to wrinkle which seriously damages the commercial value of the mounting leaf. Also, further moisture expelled from the base tends to be trapped underneath the cover sheet especially at the center of the leaf where the moisture can hardly escape. The trapped moisture affects the nature of the pressure-sensitive composition printed on the cardboard base. As a result, the adhesive composition tends to move from the base to the cover sheet, or the cover sheet, or the cover sheet firmly sticks to the adhesive-covered base and cannot be peeled off without damaging it. The damage to the properties of the adhesive composition is fatal to the commercial value of the mounting leaves. Since humidity varies widely from season to season as well as at different geographical or storage locations, the above-mentioned drawbacks present serious problems to the storing, transporting or displaying of the mounting leaves.
The problem of the shrinkage or expansion of the base has been solved by making it out of a foaming synthetic resin or a foamed rubber which, by nature, are not affected by moisture. However, the problem of the deterioration of the properties composition has not been solved. This is because the adhesive composition is normally applied over the base in the form of a pattern consisting of spaced parallel lines defining therebetween channels which allow atmospheric air to enter and affect the nature of the adhesive composition.
This drawback is particularly notable where the displayed articles, such as photographs, are mounted side by side in closely spaced relationship. Such an arrangement easily results in air being trapped between the transparent cover sheet and the adhesive composition applied over the base. The only remedy to avoid this inconvenience is to arrange the displayed articles spaced apart sufficiently to allow the transparent cover sheet to reach the space between photographs and thereby adhere to the adhesive composition.
The use of the aforesaid known mounting leaves also has the inconvenience that a certain skill is required for closing and pressing the transparent cover film or sheet against the base without the formation of air bubbles between the two. Such air bubbles mar the appearance of the entire display and furthermore make it difficult to view the attached articles properly.